Ishkur:We have got to get out of fossil fuels and into some sort of new maglev anti-grav super future wonder tech if we hope to push space exploration any further.

Not true. We can push plenty further with what we got. We have the capability to explore the oceans of moons, return samples, etc. We don't do it because too many folks don't appreciate paying for science that expands humanity's knowledge without an immediate return on investment.

Other propulsion systems should and will eventually come, but we are nowhere close to the limit of combustion rockets can achieve.

Read the article. They plan to use self landing rocket boosters in the future so that they can reuse them rather than have the boosters burn up on re-entry. Presumably that would help lower future costs.

Kimpak:Ishkur: We have got to get out of fossil fuels and into some sort of new maglev anti-grav super future wonder tech if we hope to push space exploration any further.

Psst. Rockets don't run on gas.

Yeah they do. The entire SpaceX booster family runs on RP-1 kerosene and liquid oxygen. So does the first stage of the Atlas V and the whole Soyuz family.

That's not the point, though, since the fuel is one of the cheapest parts of a rocket. Reusing the expensive engines and structures, without Space Shuttle-style refurbishing that costs as much as building new rockets, is a big deal.

If you want futuristic spaceflight, there's only one thing you have to do: cure people of nuclear phobia. 1960s nuclear thermal rocket technology blows chemical rockets out of the water, but we're to chickenshiat to put a reactor in orbit (even as an upper stage, which stays thoroughly non-radiological until it's past the point where it can fall back to Earth).

Professor Science:Kimpak: Ishkur: We have got to get out of fossil fuels and into some sort of new maglev anti-grav super future wonder tech if we hope to push space exploration any further.

Psst. Rockets don't run on gas.

Yeah they do. The entire SpaceX booster family runs on RP-1 kerosene and liquid oxygen. So does the first stage of the Atlas V and the whole Soyuz family.

cure people of nuclear phobia. 1960s nuclear thermal rocket technology blows chemical rockets out of the water, but we're to chickenshiat to put a reactor in orbit (even as an upper stage, which stays thoroughly non-radiological until it's past the point where it can fall back to Earth).

Do you have any idea how much shielding mass you would need to protect a manned version's occupants?

It's a lot - the USAF did the studies back in the 50's. And quickly rejected the idea. And this was Curtis R. LeMay we're talking about.

Marcus Aurelius:Do you have any idea how much shielding mass you would need to protect a manned version's occupants?

It's a lot - the USAF did the studies back in the 50's. And quickly rejected the idea. And this was Curtis R. LeMay we're talking about.

The Air Force studies were focused on a nuclear aircraft, which has very different design considerations from a spacecraft. The reactor and crew are forced to be fairly close to each other, it has to operate in an atmosphere that can scatter radiation, its fuel fraction is relatively low, and ground crews have to work near it after it has run recently.

Spacecraft don't face those particular issues, and a combination of distance and using reaction mass (and other supplies, like water) as shielding can pretty easily make the power plant less of a problem than solar and cosmic radiation.

Professor Science:The Air Force studies were focused on a nuclear aircraft, which has very different design considerations from a spacecraft.

It was also a very different form of reactor. Spacecraft today use radio thermal batteries which aren't very dangerous to humans. But they don't generate much power.An orion spacecraft would be detonating nukes a safe distance behind a pusher plate that's several hundred tons heavy.Solar and Cosmic radiation would be more of a concern... but then again, an Orion actually needs weight. You could use a concrete hull and it would only help to smooth out the ride.

/The problem was the fallout from launch would hurt everyone on the ground./Maybe if they could build these things on the moon or with material from an asteroid, it would be a viable space travel method.

This is why the whole "It's so sad America no longer has a real space program" idea is nonsense. SpaceX is an American company. And private entrepreneurship is part and parcel to the American way of doing things. I for one am glad that the US has taken the next step and grown past having a government space agency being the only source of spaceflight in favor of private citizens doing it on their own. Companies like SpaceX are the future of spaceflight, not just for the US but for the world.

Why does that torch on the side of the rocket outlet need to be on all the time? Would the rocket extinguish if the torch goes out, or is it kept on during flight just-in-case the propellant pressure isn't constant?

kayanlau:Why does that torch on the side of the rocket outlet need to be on all the time? Would the rocket extinguish if the torch goes out, or is it kept on during flight just-in-case the propellant pressure isn't constant?

That flame off to the side is the exhaust from the engine's turbopump gas generator. It's basically a little jet engine (heh, little compared to the main engine, anyway -- the Merlin's turbine puts out around 2500 horsepower) that provides the power to shove propellants into the engine, and its exhaust is also used for roll control.

Marcus Aurelius:Professor Science: Kimpak: Ishkur: We have got to get out of fossil fuels and into some sort of new maglev anti-grav super future wonder tech if we hope to push space exploration any further.

Psst. Rockets don't run on gas.

Yeah they do. The entire SpaceX booster family runs on RP-1 kerosene and liquid oxygen. So does the first stage of the Atlas V and the whole Soyuz family.

cure people of nuclear phobia. 1960s nuclear thermal rocket technology blows chemical rockets out of the water, but we're to chickenshiat to put a reactor in orbit (even as an upper stage, which stays thoroughly non-radiological until it's past the point where it can fall back to Earth).

Do you have any idea how much shielding mass you would need to protect a manned version's occupants?

It's a lot - the USAF did the studies back in the 50's. And quickly rejected the idea. And this was Curtis R. LeMay we're talking about.

Weren't there studies done back in those days about launching an object into space by detonating a nuclear bomb underneath it? From what I remember, they never found some of those things they tested those launch methods on. This all came with one of those codenames that I can't for the life of me remember at the moment.

TheOther:Even aside from the fact that only a relatively small amount of a Saturn V's mass reached orbit, that's a pretty frivolous answer.

Well, of course. Why would we send the entire mass into orbit? That's a waste of energy. We only need to get the necessary modules up past terminal velocity and then let go.

What this boils down to is whether a nuclear reactor and its shielding is too heavy to use as a propellant to fire anything into space. I haven't done any calculations, so we gotta ask the physics buffs whether the energy generated and directed in one direction via nuclear fusion has a better cost-benefit ratio than energy generated by ignited hydro-fuels and directed in one direction.

Ishkur:TheOther: Even aside from the fact that only a relatively small amount of a Saturn V's mass reached orbit, that's a pretty frivolous answer.

Well, of course. Why would we send the entire mass into orbit? That's a waste of energy. We only need to get the necessary modules up past terminal velocity and then let go.

What this boils down to is whether a nuclear reactor and its shielding is too heavy to use as a propellant to fire anything into space. I haven't done any calculations, so we gotta ask the physics buffs whether the energy generated and directed in one direction via nuclear fusion

fission has a better cost-benefit ratio than energy generated by ignited hydro-fuels and directed in one direction.

If anyone is willing to crack the numbers, I'm all ears.

That number crunching was done in the 60s and earlier, like I already said. They designed an engine (and ground tested it), an enlarged version of the Saturn V to put it in orbit before lighting it up, and a manned Mars mission to use it. Then Congress looked at the price tag, the fact that we had already dickslapped the Soviets with Apollo, and all the other things they could use that money for. You already know where the story goes from there.